Multiplexer Impedance Tuning With Resonator-Assisted Low Loss Matching
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Solution Overview
Problem
In multiplexers supporting multiple frequency bands, achieving low insertion loss while maintaining impedance matching is challenging, especially when using series inductors with large inductance values, which increase insertion loss.
Innovation Solution
A multiplexer configuration that includes a longitudinally coupled resonator and a series inductor, where the impedance of one filter is shifted to be inductive and the impedance of another filter is capacitive, allowing for smaller inductance values and reduced insertion loss by combining impedances at the common terminal, using a parallel resonator to adjust impedance on a Smith chart.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a series inductor with a large inductance value is provided to adjust phase and achieve impedance matching, then impedance matching is improved, but insertion loss increases
Solution Approach 1:
The patent changes the impedance parameter of the filter by adding a parallel resonator, which transforms the overall impedance characteristic. This allows the use of a series inductor with a smaller inductance value to achieve the required phase adjustment, thereby reducing insertion loss while maintaining impedance matching accuracy.
Solution Approach 2:
The parallel resonator acts as an intermediary element that modifies the impedance characteristic of the filter. By introducing this intermediate component, the patent enables the series inductor to operate with a smaller inductance value, resolving the contradiction between impedance matching accuracy and insertion loss.
2Measurement precision
If a series inductor is added to adjust phase for impedance matching, then impedance matching is improved, but device complexity increases
Solution Approach 1:
The parallel resonator serves multiple functions: it adjusts the impedance characteristic of the filter and enables more efficient phase adjustment by the series inductor. This multi-functionality reduces the need for additional components, thereby limiting the increase in device complexity while achieving improved impedance matching.
3Loss of energy
If inductance value of the series inductor is reduced to decrease insertion loss, then insertion loss is reduced, but impedance matching accuracy deteriorates
Solution Approach 1:
The patent changes the impedance parameter of the filter by adding a parallel resonator, which transforms the overall impedance characteristic. This allows the use of a series inductor with a smaller inductance value to achieve the required phase adjustment, thereby reducing insertion loss while maintaining impedance matching accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration achieves accurate impedance matching and reduces insertion loss, allowing for a multiplexer with smaller inductance values and lower signal leakage across frequency bands.
Implementation Method 1
impedance of the first filter that is shifted to be inductive by the inductor, and capacitive impedance of the second filter are combined at the common terminal
Implementation Method 2
The first filter includes a longitudinally coupled resonator formed of one or more first resonators and a plurality of second resonators disposed on both sides of each of the first resonators
Data Source
AI summary
Filters 10 and 20 having respective pass bands different from each other, a common terminal to which a terminal 11 of the filter 10 and a terminal of the filter 20 are connected, and an inductor of which one end is connected to the terminal 11 and another end is connected to the common terminal. The filter 10 includes a longitudinally coupled resonator formed of a resonator 132 and resonators 131 and 133 disposed on both sides of the resonator 132, in which the resonator 132 is connected to the terminal 11, and a parallel resonator of which one end is connected to the resonator 132 and another end is connected to a ground electrode, and the resonator 132 and the parallel resonator of the resonators included in the filter 10 are connected to a signal path between the resonator 132 and the terminal 11.